1. Field of the Invention
The present invention relates to a method of manufacturing a capacitor, a capacitor, and a method of forming a dielectric film used in the capacitor.
2. Description of the Related Art
Recently, from demands for high integration and high speed LSI (large-scale integration), design rules of a semiconductor device configuring the LSI have been miniaturized further. Accompanying with this, increase of a capacity of a capacitor used in a DRAM is requested, and accordingly, increase of dielectric constant of a dielectric film used in the capacitor is also required.
As a dielectric film having high dielectric constant and used in such a capacitor of a DRAM, a zirconium oxide (ZrO2) film is suggested (for example, as in Patent Document 1).
However, in a case where a ZrO2 film alone is applied as a dielectric film of a DRAM capacitor, the ZrO2 film cannot meet the high-K property required as a dielectric film of a next generation DRAM. Thus, a titanium oxide (TiO2) film having higher dielectric constant is highlighted as a next generation dielectric film (for example, as in Patent Document 2).
Also, Patent Document 3 discloses a capacitor using a two-layered metal oxide film that contains Ti such as a ZrO2 film or a TiO2 film as a dielectric film.
As disclosed in the Patent Document 2, when the TiO2 film is used as the dielectric film, there is a problem that the TiO2 basically has a high leakage current and low stability. Thus, to address the above problem, a technology of mixing a dopant such as AlO with TiO2, using a RuO2 film as an electrode material, or forming a Ru film or a Pt film as a base film is being researched; however, the above technology may not provide a sufficient property or have a high technical hurdle. Thus, the DRAM capacitor using the dielectric film that mainly includes the TiO2 film has not been commercialized yet.
Also, since the ZrO2 film is likely to generate oxygen deficit, even if the dielectric film having a two-layered metal oxide film including Ti such as the ZrO2 film and the TiO2 film as disclosed in the Patent Document 3 is used, it is difficult to achieve a desired level of high dielectric constant and low leakage current.    (Patent Document 1) Japanese Laid-open Patent Publication No. 2001-152339    (Patent Document 2) Japanese Laid-open Patent Publication No. 2004-296814    (Patent Document 3) International Application Publication No. 2010/082605 Pamphlet